Low-temperature defrosting system



Land;

March 18, 1952 PABsT 2,589,855

LOW-TEMPERATURE DEFROSTING SYSTEM Filed Dec. 12, 1949 8a' fi /0 W9 --I hi v Ez'chardEPaZsZ, J i

ATTOR N EY- Patented Mar. 18, 1952 UNITED STATES PATENT OFFICELOW-TEMPERATURE nsrsosrmo SYSTEM Richard E. Pabst, San Antonio, Tex.Application December 12, 1349, Serial No. 132,429 3. Claims. (01. sa-115) frigerant in the systemwhereby the condenser and the evaporatortemporarily exchange their functions so as to defrost the evaporator.

In order for that system to operate, a thermostatic valve and a backcheck valve were included in the defrigerant circuit adjacent theevaporator and a capillary tube and a back check valve were included inthe refrigerant circuit between the outlet of the condenser and theinlet of the receiver. In practice it was found that in the defrostingphase the return of the liquid from the coil being defrosted was slowedup. My present invention has for its object to remedy this defect bysubstituting for the capillary tube and back check valve between thecondenser and receiver a service valve located in the receiver by meansof which a liquidspray and gas mixture will be supplied to the condenserwhen the system is being operated in the defrosting phase. In this waythe removal of the gas pressure above the liquid in the receiverprovides for a more rapid return of liquid from the coil beingdefrosted.

More specifically, my invention resides in the elimination of thecapillary tube and its association check valve, and the provision of ashort tube extending into the receiver and terminating well above theliquid level with a syphon tube extending into the liquid, and assembledwith the short tube, with the syphons upper end projecting into thelower end of the short tube.

In the drawing:

Fig. 1 is a schematic view of a refrigerating system embodying mypresent invention.

Fig. 2 is an enlarged cross section on the line 22 of Fig. 1.

In the drawing, in which like numerals and letters of reference indicatelike parts in all the figures, the evaporator coil 1 has one end Iconnected toa thermostatically operated expansion valve 2 and to aone-way check valve 3, the valves 2 and 3 being connected, in parallel,to the coil end l and to the beginning or entrant end 4* of a pipe 4which passes through a cylinder 6 and has its other end i -passed into areceiver 10 to extend below the liquid level therein (see Fig. 1). Theotherend of the evaporator coil 3 is connected to a pipe 5 which alsopasses through the cylinder 6 in proximity to the pipe l and continuesto a port of a reversing valve (8 of suitable construction, such as thatdisclosed in my application Ser. No. 93,123, filed May 13, 1949, forexample. The portions of the pipes 4 and 5 'which'arecontained withinthecylinder 5 constitutetherewith a heat exchanger.

The condenser has one end l of its coil I connected to a short tube 8whose lower end terminates well above the liquid level in the receiver.A syphon tube 9 has its upper end curved, as at S and welded orotherwise secured in a slot 3a in the lower end of the tube 8; the upperend 9*- discharges into the tube 8 at its lower end, while the lower endof the tube 9 extends well below the liquid level in the receiver H).

The other end of the condenser 1 connects with a pipe l that extendsfrom a port of the reversing valve l8.

12 indicates the compressor, l3 the motor which drives it via a belt andpulley connection 14. The high side of the compressor is connected to aport of the reversing valve by means of a pipe IS. The low side of thecompressor is connected with ports of the reversing valve via pipes l6and H. The motor base is indicated 1 In the normal operation of thesystem the valve I8 is set to cause communication between pipe 15 andpipe I and between pipe 5 and pipe 16. Therefore the compressedrefrigerant (gas) flows from the compressor via pipe l5, valve l8, pipe1*, to condenser l where it is liquefied. From condenser 1 therefrigerant flows through my new valve 8-9 into the receiver I0, fromwhich the defrigerant in the liquid phase passes via pipe 4, heatexchanger 6, thermostatic valve 2, pipe I, into the evaporator where therefrigerant becomes evaporated, the refrigerant in the gaseous phaseflowing from the evaporator via pipe 5, valve l8, pipe [6, to thecompressor I2.

In the defrosting phase, the refrigerant from the compressor I2 passesthrough pipe 15, valve 18, pipe 5, heat exchanger 6, evaporator 5, checkvalve 3, pipe 4, to the receiver 10. From the receiver liquidrefrigerant passes up the syphon tube 9 into the pipe 8, from which airand liquid spray passes into the condenser l and from the condenser, viapipe 1, valve l8, pipe I1,

to pipe l6 and back to the compressor l2. At this time pipe l6 has nodirect connection to the valve l8. As the pressure of the air in thereceiver or reservoir is thus relieved, little or no back pressure onthe flow of the refrigerant from the evaporator to the receiver willretard such fiow. From the foregoing description, taken in connectionwith the accompanying drawing, it.;is thought that the construction andadvantagesiqf my invention will be clear to those skilled in-the art towhich it appertains. What I claim is:

1. In a refrigerating system, an evaporawr, a condenser, a compressor,and a receiver, operatively connected in circuit with a reversing meansfor reversing the flow of refrigerant in the evaporator and condenser:combined with means located in the receiver and operable in the reversephase for reducing the gas pressure in the receiver, said last namedmeans comprising a pipe connected with a duct leading from the condenserto-the receiver, the inner end of said pipe terminating well above theliquid level in their}?- ceiver and a syphon tube having an endconnected to said pipe to discharge into the same and having its otherend located well below'gthe liquid level in the receiver. 2. Inreverse-cycle-defrosting refrigerating systems, an evaporator, acondenser, and a receiver having a pipe leading from said evaporator andextending into thereceiver well belowthe liquid level in the receiver, asecond pipe secured to the shell of the receiver and connected to saidcondenser, a short pipe within the receiver secured at one end to saidsecond pipe and having its other end terminated well above the liquidlevel in the receiver, and a syphon tube connected to said short pipe atits inner end to communicate with the same, said syphon tube extendingwell below the liquid level in the receiver.

3. In a refrigerating system, anfevaporator, a condenser, a compressor,and a receiver, operatively connected in circuit with a reversing meansfor reversing the flow of refrigerant in the evaporator and condenser, apipe leading from said evaporator and extending'into said receiver belowthe liquid level in the receiver, a second pipe connected to saidcondenser and extending into said receiver and having its endterminating above the liquid level in the receiver, and a siphon tubeconnected to said second pipe and having communication therewith, saidsiphon tube extending below the liquid level in said receiver andcontrolling gas pressure and liquid flow from said receiver to saidcondenser.

RICHARD E.- PABST:

REFERENCES CITED The following references are of record in the file ofthis patent: I V UNITED STATES PATENTS Number Name Date 1,533,336Pownall Apr. 14, 1925 1,884,186 Peltier et a1. Oct. 25, 1932 2,444,514Kubaugh July 6, 1948

